As a rule, such ceramic substrates are formed in several layers. For this purpose, homogeneous tape layers, i.e., tape layers having the same composition, are positioned on top of one another, laminated, and sintered. The tape layers are usually composed of a system of oxide glasses, such as of a mixture of Al2O3, SiO2, and CaO. These precursor substances of the ceramic substrate are chemically converted during sintering, forming crystalline phases, such as the crystalline silicate anorthite (CaO.Al2O3.2SiO2). In practice, planar multi-layer ceramic substrates are produced that way.